The present invention relates to an improved launching pad for guided missiles to combat airborne targets and in particular low-flying aircrafts.
In the defense against low-flying targets (aircraft, missiles, helicopters) there often arises the situation that the associated elevated observation unit (usually the antenna of a radar instrument) detects and follows a target, but that, at the given moment, obstacles, such as uneven terrain, growth or buildings utilized as camouflage, for example, are disposed in the path of flight of the missile for a hit using a line-of-sight method or a collision-course method. In order to employ the missile successfully, it is then necessary either to delay firing until the target has come closer and the necessary flight path is free of obstacles or the missile must be fired with a higher elevation immediately upon detection of the flying object and then guided in the direction toward the target.
Waiting for the target to come closer results in a reduction of the defense perimeter, possibly to the limits of the "inner dead zone", which is the area surrounding the firing location in which an approaching aerial target can be located without being able to be successfully attacked by a missile. The "inner dead zone" results from the fact that an aerial target which has penetrated to the immediate vicinity of the firing location can no longer be hit by a missile because the large curvature in the missile flight path, which may be required under certain circumstances due to the statistical deviations of the missile flight paths, would cause high transverse acceleration forces to be exerted on the missile which could thus overstress the structure of the missile. The magnitude of the "inner dead zone" thus depends on the speed of the approaching target and on the target finding method employed for the missile, and a redirection of the missile in the direction toward the target reduces the "inner dead zone".
In the above-mentioned air defense guidance weapons systems it is obviously desirable to have the "inner dead zone" as small as possible. Accordingly, to minimize the "inner dead zone", the missile must be brought as quickly as possible from the launching pad into an attack position which is defined by a predetermined height above the firing level and by a limited inclination of the longitudinal axis of the missile with respect to the horizontal. The height here approximately corresponds to that of the low-flying aerial target, and the permissible inclination for missiles with homing guidance systems depends on the viewing angle of the target finding head.
Substantially, three different modes of operation are known for the guidance of a missile:
1. The aerodynamic guidance may be realized by means of a fixed or controllable deflection of control surfaces disposed on the body of the missile which produces a turning of the missile, thus effecting a change in the path of flight via a change in the angle of incidence and the sweep action of the thrust vector. Since the aerodynamic forces, and thus also the control moment, increase with the square of the velocity, the path of flight is initially stretched out or straightened and later curved more strongly. This results, however -- since the change in direction is effected at high speeds -- in an increased mechanical stress on the structure of the missile due to heavy transverse acceleration forces. Moreover, with a fixed power phase for the driving system, the possible final speed, and thus the effective range of the missile, is reduced since the longitudinal inclination of the missile required for redirection with respect to the tangent of the path and the raised guide surfaces also increases the aerodynamic resistance of the missile.
2. A further possibility to initiate a control moment for the missile is by the sweep of the thrust vector. By changing the direction of the thrust jets, the effective line of the thrust no longer passes through the center of mass of the missile and thus produces a pitch moment which results in a pitching movement and thus a curvature in the flight path. After a desired period of flight, the thrust vector is then returned to the zero position by returning the thrust jets to their normal position. The difficulties of such an arrangement, however, lie in the requirement for very accurate alignment of the thrust jet. This is a result of the fact that, due to the large thrust involved, small angular deviations in the direction of this thrust cause great changes in the pitch moment and, since only slight control moments are necessary, slight angular deviations in the direction of thrust cause very strongly differing flight paths (dispersion).
3. One can also provide additional thrust jets which are disposed in a direction perpendicular to the longitudinal axis outside of the pitch axis, and which produce a constant transverse thrust and thus a pitch moment. The transverse thrust produced by these additional jets is then cut off after a desired duration of the power phase. This arrangement, however, requires additional constructive expenditures and results in a weight increase for the missile.